User Accounts gone from Log On Screen

My wife and I share a laptop. We are using W7 Home Premium. I have an account set up for her, for me and when we logon to the computer, there are buttons for each of our accounts, plus a third one that I honestly can't say what it was, Guest, Other, Administrator, not sure.

Anyway, today, without making any changes that I am aware of, now it only has one account button and an Other button, which you can click on and enter an account name. So, if the logon button is me, she can click on Other and enter her name and then logon. When she clicks Switch User, then it goes back to the logon screen and shows her account button and Other, which if I want to get on, I need to click and enter my name. (Since it's only the 2 of us and no one else uses our computer, we don't use passwords.)

What could have happened to showing both accounts at the same time? The only thing I can think of is my sister let me borrow her Flip Video camera and I loaded the software from it. After using it for a few minutes, I uninstalled it. Could something have happened during that? Any help would be appreciated. Thanks.

From the Microsoft Answers Forum:
Seberle,
I had the same issue and was all over the forums trying to find an answer. I managed to fix it by deleting a key from the registry. Click the Start menu and type regedt32. Navigate to the following key.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
In the profile list, there was one named .DEFAULT with no data within it. I deleted this key rebooted and all of my user icons were back on the logon screen. Of course, you should have a backup of the registry key before deleting. I don't know why this suddenly changed.

I went to this location in the registry and there were 2 default listings:
Name Type Data
(Default) REG_SZ (value not set)
Default REG_EXPAND_SZ %SystemDrive%\Users\default

I didn't know which to delete, so after making a backup, I tried each one and it wouldn't allow me to delete either one. I also could not logon as Administrator, so not sure where to go from here. Thanks for your help.

It is not clear if you have any Administrative users, you and wife are Standard Users?

Could try - Open User Accounts - by clicking the Start , clicking Control Panel, clicking User Accounts and Family Safety, clicking User Accounts, and then clicking Manage another account. You should see a list of users with Administrator privileges. You will need to know the password for one of the users listed.